... electricity, railway, highway engineering, etc. This series use single booms to drill, with high efficiency and speed which ... cannot only drill blast hole, on the basis of section, with our patent impeller, the jumbo can drill ... stability. It is specially suited to tunnels of small section.It can walk flexibly with direct diesel drive, ... (m)2.1 (standard)2.1( standard)Cross section W×H (m×m)2×2- 3.5×3. ...